Estimation of the Variability of the Combined Electron and Positron Flux of Cosmic Rays
- PDF / 1,187,392 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 29 Downloads / 192 Views
E PLASMA
Estimation of the Variability of the Combined Electron and Positron Flux of Cosmic Rays V. M. Loznikova, * and N. S. Erokhina a Space
Research Institute, Russian Academy of Sciences, Moscow, 117997 Russia *e-mail: [email protected]
Received December 17, 2018; revised February 7, 2019; accepted March 20, 2019
Abstract—The variability of the combined electron and positron flux (e+ + e–) of cosmic rays (CRs) is numerically estimated using the results obtained in the Fermi-LAT, AMS-02, and DAMPE satellite experiments. The validity of the variability of the (e+ + e–) CR spectra in the energy range of >30 GeV is demonstrated. Correlation between the reliability of the variability for each pair of spectra and the difference of the average monthly sunspot numbers averaged over the time interval of observation is established. The existence of the observed variable component of the (e+ + e–) CR flux on a time scale from ~1 month to ~1 year can be explained using the model of surfatron acceleration of CRs in the close neighborhood of the Solar System (at the periphery of the heliosphere and in the nearby interstellar clouds). DOI: 10.1134/S1063780X19090058
1. INTRODUCTION The latest generation of cosmic ray (CR) detectors (those launched on aerostats or satellites, along with huge ground-based facilities) brought about considerable improvement of sensitivity and energy resolution, thereby enabling one to record the variable features of CR spectra. A broad quasi-peak in the (e+ + e–) CR spectrum in the vicinity of ~700 GeV was first reliably detected in the ATIC balloon experiment [1] and later confirmed in the PPB-BETS balloon experiment [2]. Considerable changes in the electron (e–) and positron (e+) CR spectra were subsequently detected in the PAMELA [3–5], Fermi-LAT [6, 7], and AMS-02 [8, 9] satellite experiments. Recently, new data obtained in the Fermi-LAT [10], DAMPE [11], and CALET [12] experiments in the energy range of up to several TeV were reported. The spectra confirmed the presence of a broad quasipeak in the vicinity of ~1 TeV. At higher energies, the particle flux was found to drop abruptly. However, there is a clear tendency showing that the spectrum extends beyond 10 TeV. It is commonly accepted that sources of (e+ + e–) CR with energies of >10 GeV are remnants of supernova and pulsars. We will not discuss here exotic models based on the concept of dark matter. The closest pulsar Geminga lies at a distance of ~250 pc. If a source of (e+ + e–) CRs is located at a distance of >1000 pc, both e+ and e– loose their energy upon propagation to the Earth due to synchrotron emission of radiation in
the interstellar magnetic field and Compton scattering from the microwave background. By now, the (e+ + e–) CR spectra have been measured up to an energy on the order of several TeV. The Larmor radius for electrons with an energy of ~1 TeV is ~100 AU (or ~10–3 pc). Even for an energy on the order of the “knee” energy (~106 GeV), the cyclotron radius is only ~1 pc. Therefore, all specific features of the spect
Data Loading...
